Silage cutter

ABSTRACT

A silage cutter comprises a fame consisting of first and second frame members which are adapted to be moved relative to one another about a hinge axle by means of drive mechanisms, said drive mechanisms comprising two hydraulic cylinders. The first frame member has a knife attached thereto. The second frame member has provided thereon gripping devices for gripping the silage. A hydraulic device causes the two cylinders always to have the same length.

[0001] The present invention relates to a silage cutter according to the generic clause of claim 1.

[0002] In the device known from EP 0 506 158 A, the distance between the hinge axle and the part of the gripping devices which is most remote from said hinge axle corresponds to the distance between the hinge axle and the knife. The two cylinders, which are driven for bringing together the first and second frame members for a silage cutting operation, are hydraulically controlled via a directional control valve in such a way that, if one cylinder is in advance, the application of pressure to said cylinder will be throttled or interrupted until both cylinders move in synchronism. For this purpose, sensors are provided on both sides of the first frame member, which are connected to the rerouting sides of the directional control valve. An adaptation of the cylinder movements is only effected after a preceding deviation in the movements of the two cylinders; this causes deformations or transverse displacements at the frame members which have to be eliminated afterwards. This influences the cutting result and causes undesirable high loads in the device. An additional fact is that, due to the dimensions of the distance, the knife will not neatly co-operate with the gripping devices towards the end of the cutting operation, but an undefined cutting condition will occur. The frame members must be extremely robust, a circumstance which entails further disadvantages. According to a further embodiment, at least one knife is provided, which is adapted to be moved to and fro during the cutting operation and which carries out a sawing movement; this knife, however, requires inexpedient dimensions transversely to the cutting direction.

[0003] Additional prior art is contained in DE-U-29 719 753, EP 0 779 027 A and in EP 0 359 482 A.

[0004] It is the object of the present invention to provide a silage cutter of the type cited at the start in the case of which a stationary knife is forced through the silage and in the case of which a comparatively light frame can be used nevertheless.

[0005] This object is achieved by the features of claim 1.

[0006] Since it is guaranteed that the frame members provided on the two sides approach each other at exactly the same speed and independently of the reaction forces occurring, strong cutting forces can be produced without any disadvantageous deformation of the frame. Hence, stationary knives can be used, which are very flat and thin and which will easily cut through the silage. Due to the relative distance defined between the pivot axle and the knife on the one hand and between the pivot axle and the most remote point of the gripping device on the other, a defined cutting condition is obtained at the end of the cutting operation, said defined adding condition being also supported by the cylinders which move exactly in synchronism.

[0007] When the cylinders are connected in series, there will always be a fixed relation between the amount of pressure medium supplied to one cylinder and the amount of pressure medium supplied to the other cylinder. The diameter of one of said cylinders should be smaller than the diameter of the other cylinder so that the pressure medium which is displaced by the piston of one cylinder and which acts on the other piston-rod side of the piston of the other cylinder produces identical speeds of the two cylinders.

[0008] When the cylinders are connected in parallel, hydraulic means guarantee that the cylinders move in synchronism; the cylinders, can then be dimensioned identically.

[0009] It will be expedient to provide hydraulic devices which limit the maximum pressure in each cylinder or the pressure difference between the two cylinders to a set value. This will additionally protect the frame against excessive deformation.

[0010] Advantageous kinematic conditions are obtained when the distance between the hinge axle and the articulation point of the cylinders on the first frame member is larger than half the distance between the hinge axle and the knife. It will be expedient when this distance is even larger than two thirds, or even larger than three quarters of the distance between the hinge axle and the knife. The distance between the hinge axle and the articulation point of each cylinder on the first frame member corresponds almost precisely to the distance between the hinge axle and the knife, minus the desired silage cutting depth, i.e. the thickness of a slice of “silage” out by the knife.

[0011] Advantageous kinematic conditions, which are important for high cutting forces and distortion-free cutting, will also be obtained on the second frame member if the distance between the hinge axle and the articulation point of the cylinders on the second frame member is in any case larger than half the distance between the hinge axle and the gripping devices. This distance should even be larger than two thirds, and, if necessary, it should even be larger than three quarters of the distance between the hinge axle and the gripping devices.

[0012] The cutting quality will be improved when the first frame member has provided thereon at least one lateral knife, which is fixedly attached to said frame member and which extends almost at right angles to the transversely extending main knife and is oriented almost radially to the hinge axle. The knife and the two lateral knives are arranged such that they define a U-shape. The lateral knife may have a curved cutting surface.

[0013] The cutting edge of the knife and/or of each lateral knife may be straight or it may have a curved shape. Preferably, said cutting edge may have individual parts which extend at a certain angle relative to one another and which define e.g. a knurled or a wavy cutting edge. Good cutting results can be achieved by knives and lateral knives, respectively, in the case of which the distance between forwardly extending portions of the cutting edge is smaller than 8 cm, or even smaller than 6 cm, or, even better, smaller than 4 cm.

[0014] The knife may be a metal plate on which the cutting edge is defined by an edge-side bevel of said plate. The bevel should be located on the side facing away from the hinge axle so as to achieve a good cutting quality.

[0015] The second frame member is provided with one or with a plurality of cutting devices which are intended to co-operate with the knife and/or the lateral knives of the first frame member. When the cutting edge of each knife moves against or almost against one of these cutting devices at the end of the cutting operation, the silage will be cut neatly.

[0016] At one edge of the cutting device, the cutting edge of the knife or of the lateral knife will move in such a way that a scissorlike cutting movement or a drawing cut will be obtained. The cutting device may be provided with an immersion groove for the cutting edge of the knife and of the lateral knives, respectively; the cutting edges need not touch the bottom of the groove, since a good cut is already effected at the edges. The gripping devices define a kind of loading flap and have a platelike member provided with a sharp edge or teeth which is/are adapted to be pressed into the silage block. It will be expedient to implement the platelike member such that it does not have any openings so that the cut-out silage will drop on said platelike member for being then transferred in its entirety to a mixing chamber of the silage cutter.

[0017] When the differential distance mentioned at the beginning is at least 5 cm, or even better 15 cm, a substantial part of the gripping device will still be located in the uncut silage when the cutting operation has almost been finished. In addition, the knife and the lateral knives cooperate very effectively with the gripping devices.

[0018] Even if comparatively strong cutting forces are generated by the hydraulic cylinders, the guide mechanisms will assist in the formation of a neat cut because the frame members are guided along one another and will not move parallel to the hinge axle nor deform.

[0019] A stop of the guide mechanism permits an exact adjustment of the end of the movement of the knives. At the end of a cutting operation, the knives, as soon as the stop becomes effective, have carried out a movement corresponding to almost their whole effective length up to a point located very close to the cutting devices so that the whole silage located below the knife is neatly cut through.

[0020] Part of the mixing chamber used for depositing the cut-out silage is defined by the second frame member.

[0021] It will be expedient when the second frame member is tiltably secured to the mixing chamber by means of a hinge so that the cut-out silage can be deposited in the mixing chamber by tilting the second frame member. The mixing chamber may have provided therein a mixing device and/or other devices for treating the silage.

[0022] Alternatively, the second frame member can be connected to the mixing chamber in a more or less stationary manner and define the bottom of said mixing chamber, whereas the first frame member is equipped with a loading flap which is pivotable on arms, the knife being secured to the edge of said loading flap. For connecting the loading flap to the first frame member, a hinge or a sliding mechanism can be used. The second frame member can define an approximately flat extension of the bottom of the mixing chamber on which the cut-out silage is deposited.

[0023] When travelling, the silage cutter is supported by ground support wheels. By means of a suitable adjustment device, the silage cutter can be adjusted approximately vertically relative to the wheels. In this way, it is possible to lower the gripping devices until they touch the ground and to push them along the ground up to and below the silage to be cut out. Losses will be avoided in this way. For transporting the cut-out silage, the silage cutter can be raised on said wheels so as to be easily movable.

[0024] If the cut-out silage is transferred to the mixing chamber making use of the fact that the second frame member is pivotable on said mixing chamber with the aid of two hydraulic cylinders, control valves, e.g. check valves, should be provided in the pressure-medium supply conduits of these cylinders so that the length of the two cylinders and, consequently, the respective pivotal position of the second frame member can be fixed in relation to the mixing chamber at least temporarily.

[0025] A precise synchronous movement of the two cylinders, which have to produce the cutting forces and which are connected in parallel, is achieved by means of a hydraulic flow divider supplying to the two cylinders identical pressure medium flows, irrespectively of the extent to which the counterforces at the two cylinders may perhaps differ from one another. In comparison with a directional control valve, which is only actuated in response to a deviation from a condition of synchronous movement so as to eliminate said deviation, the flow divider has the advantage that there will be no deviation from a synchronous movement because, if the counterpressure at one cylinder increases, the flow divider will supply this cylinder, irrespectively of the increasing counterpressure, with the same amount of pressure medium as the other cylinder so that a relative advance will be excluded.

[0026] However, in order to prevent the silage cutter from being damaged, if, for some other reason, e.g. an obstacle would become effective on one side of the silage cutter, pressure-limiting valves are provided, which limit the maximum pressure in each cylinder and/or the maximum differential pressure between the cylinders and which will therefore respond automatically to an emergency situation.

[0027] Also if the cylinders are connected in series, both cylinders should be supervised by pilot-controlled pressure-limit valves defining equalizing valves so as to reduce excessive pressures and avoid damage in the event of an emergency situation.

[0028] It is part of the present invention that a silage cutter is controlled in such a way that a stationary knife on the first frame member is forced through the silage until said silage is finally cut through completely against gripping devices of the second frame member. The cutting forces are produced by two spaced cylinders, which are controlled such that they always have the same length, whereby a distortion of the frame of the silage cutter or deformations are avoided. For this purpose, the two cylinders are hydraulically controlled in such a way that, irrespectively of their individual counterpressure, they will be moved at the same speed and will always correspond in length to one another.

[0029] Since in cases where the cylinders are connected in parallel and pressure-medium flows are apportioned to the cylinders via the flow divider, a 100% distribution cannot be guaranteed due to production-dependent and function-dependent tolerances, especially in the case of cylinder strokes of up to 200 mm and more, it may be expedient to associate, during silage cutting, a downstream compensating control valve with the flow divider, said compensating control valve throttling, if necessary up to complete blockage, the flow to the respective cylinder operating against the lower counterpressure on the supply side. This permits, at least during silage cutting, a largely ideal synchronous movement.

[0030] Alternatively, the cylinder operating against the lower counterpressure during silage cutting can intentionally be biased or decelerated on its discharge side; this is achieved either via a brake valve adjusted by a differential-pressure compensating control valve and located in the blocking conduit of the respective cylinder that leads to the common discharge conduit, or by a compensating control valve which is directly connected to the discharge conduits, or by biased control valves which are arranged directly in said discharge conduits and which are controlled crosswise from the operating conduits. Interventions on the discharge sides of the cylinders have, in the case of synchronous operation control processes, the advantage that only small pressure-medium volumes or comparatively low pressures have to be governed.

[0031] Embodiments of the subject matter of the invention and, at the beginning, a conventional, known drive mechanism are explained making reference to the drawings in which:

[0032]FIG. 1 shows a known hydraulic scheme of a silage cutter at the neutral position and after the execution of a cutting operation.

[0033]FIG. 2 shows a hydraulic scheme of a drive mechanism according to the present invention for a silage cutter,

[0034]FIG. 3 shows another embodiment of a hydraulic scheme of a drive mechanism according to the present invention,

[0035]FIG. 4 shows a further embodiment of a hydraulic scheme of a drive mechanism according to the present invention,

[0036] FIGS. 5-7 show a first embodiment of a silage cutter at a read-to-cut position, at a position at the end of a cutting operation, and at a transport position,

[0037] FIGS. 8-11 show enlarged representations of details of the embodiments of FIGS. 5 to 7,

[0038] FIGS. 12-15 show a further embodiment of a silage cutter at a ready-to-cut position, at a position at the end of a cutting operation, at a transfer position for the cut-out silage, and at a transport position,

[0039] FIGS. 16-18 show a further embodiment of a silage cutter at a position at the end of a cutting operation and at a transport position, and

[0040] FIGS. 19-21 show a further embodiment of a silage cutter at a ready-to-cut position, at a position at the end of a cutting operation, and at a transport position.

[0041] FIGS. 22-25 show further hydraulic schemes for drive mechanisms of a silage cutter according to the present invention, each at a pressureless neutral position.

[0042]FIG. 1 shows two hydraulic cylinders 1 and 2 of a known hydraulic system which are arranged between two frame members of a silage cutter (not shown) so as to move these two frame members about a common hinge axle. The two cylinders 1 and 2 are shown at their retracted position at the end of a cutting operation, at which the pistons 3 and 4 are completely retracted in the cylinders 1 and 2. For adjusting a ready-to-cut position, the piston rods of the pistons 3, 4 are extended; during the cutting operation, the piston rods are retracted until they have reached the position shown. The cylinders 1 and 2 are actuated by the control valve 5 which, in the embodiment shown, is a 4/3-way control valve between a supply conduit 6 and a discharge conduit 7 on the one hand and operating conduits 8, 11 on the other. The operating conduit 8 branches and defines conduits 9 and 10 which lead to the piston-side chambers of the cylinders 1, 2, a respective branch conduit leading from each of said conduits 9, 10 via a shuttle valve 12 also to the other operating conduit 11. Connection conduits lead from the shuttle valves 12 to the piston-rod-side chambers of the cylinders 1, 2.

[0043] When the control valve 5 is moved to the right, the supply conduit 6 is connected via the operating conduit 8 and the conduits 9, 10 to the piston-side cylinder spaces below the pistons 3, 4. The pistons 3, 4 are displaced upwards. The shuttle valves 12 are forced into their upper position so that the pressure medium expelled by the pistons 3, 4 is forced downwards into the conduits 9, 10 whereby the expelling movement of the piston rods will be accelerated. In this way, the first frame, which is not shown, will assume its ready-to-cut position more rapidly.

[0044] When the directional control valve 5 is, subsequently, moved to the left, the supply conduit 6 will be connected to the operating conduit 11, whereas the operating conduit 8 will be open towards the discharge conduit 7. The shuttle valves 12 are forced into their lower positions so that the pressure medium will be transferred to the piston-rod-side chambers of the cylinders 1, 2 above the pistons 3, 4. The pistons 3, 4 move downwards. The expelled pressure medium flows via the conduits 9, 10 and the operating conduit 8 into the discharge conduit 7. In the course of this process, silage is cut out. The shuttle valves 12 contain balls which, due to the higher pressure, are pressed onto a respective valve seat and which block in this direction of flow. Since the individual counterforce at each cylinder 1, 2 can be different from the counterforce at the other cylinder and since the pressure medium from the operating conduit 8 takes the way of least resistance, the cylinder 1, 2 acted upon by the higher load will lag behind, whereas the cylinder 1, 2 acted upon by the lower load will move faster. This results in a distortion of the frame of the device or in an undesirable deformation. This disadvantage is taken into account by an excessively stable structural design of the frame; the cutting quality may, however, deteriorate substantially especially towards the end of a cutting operation.

[0045]FIG. 2 shows a hydraulic scheme for a silage cutter according to the present invention in the case of which a difference in the lengths which the two cylinders 1, 2 have during the downward movement of the pistons 3, 4 is hydraulically avoided.

[0046] The way in which the directional control valve 5 is connected to the conduits 6, 7 and the operating conduits 8, 11 in the area of the directional control valve corresponds to the connection pattern described above. The first difference is to be seen in an equalizing valve 19 provided between the operating conduits 8, 11 and implemented as a pressure-limiting valve which is pilot-controlled in the direction of flow from operating conduit 11 to operating conduit 8 and which is spring-loaded in the closing direction. In addition, the equalizing valve 19 can be pressurized via a pilot conduit 18 by a pilot pressure in the closing sense. The two conduits branching off from the conduits 9, 10 and extending across the shuttle valves 12 are not connected directly to the operating conduit 11, but they are connected via branch conduits 15, 16 to two separate connections of a flow divider 14 whose central connection communicates with the operating conduit 11. In addition, a differential pressure valve 17 is provided between the branch conduits 15, 16, said differential pressure valve feeding the pilot conduit 18 at a central connection.

[0047] If the directional control valve 5 is moved to the left (cutting position), the supply conduit 6 is connected to the inlet of the flow divider 14 via the operating conduit 11. The flow divider apportions to the branch conduits 15, 16 identical pressure medium flows which pressurize the piston-rod-side chambers above the pistons 3, 4 of cylinders 1, 2 in the pressed-down condition of the shuttle valves 12. The identical pressure medium flows are apportioned irrespectively of whether the reaction forces at the cylinders are identical or different. This means that the two pistons 3, 4 will move synchronously and that the two cylinders 1, 2 will always have the same length. A distortion of the frame or an inclined position of the knife of the silage cutter will be avoided in this way. If the individual resistance at one of the cylinders should become excessively high for some reason or other (risk of a detrimental deformation of the frame of the device), the differential pressure valve 17, which permanently compares the pressures in the two branch conduits 15, 16, will respond. In response to an adjustable value of the differential pressure between the two branch conduits 15, 16, a signal will be transmitted via the pilot conduit 18 to the equalizing valve 19, so that said equalizing valve will be set to a position allowing passage, whereby the operating conduit 11 will be opened towards the operating conduit 8 and, consequently, towards the discharge conduit 7. Pressure medium is discharged from the operating conduit 11 so that a predetermined pressure difference will not be exceeded. The pressure difference can be limited to a maximum of e.g. 50 bar.

[0048] In FIG. 3, the two hydraulic cylinders 1, 2 are connected in series. This system is also referred to as “master and slave”; cylinder 1 is here the “master” whose movement during the retracting movement of piston 3 is automatically imitated by piston 4 in cylinder 2, the “slave”. The directional control valve 5 supplies pressure medium from the supply conduit 6 to one of two operating conduits 21, 24 alternately, whereas the respective other operating conduit is connected to the discharge conduit 7. The operating conduit 21 leads to a shuttle valve 25, the piston-rod-side space above piston 3 of cylinder 1 being pressurized from the central connection of said shuttle valve 25. The piston-side space below piston 3 of cylinder 1 is connected via a conduit 22 to the piston-rod-side space of cylinder 2 above piston 4. The operating conduit 24 leads to the upper connection of the shuttle valve 25 and via a branch conduit 23 to the piston-side space below piston 4.

[0049] As soon as the shuttle valve 25 is moved to the right, the supply conduit 6 is connected to the operating conduit 26, whereas the operating conduit 24 is connected to the discharge conduit 7. The shuttle valve 25 is forced upwards so that the piston-rod-side space above piston 3 of cylinder 1 will be pressurized by the pressure medium from the operating conduit 21. The pressure medium expelled by piston 3 is supplied via the conduit 22 to the piston-rod-side space above piston 4 of cylinder 2. The pressure medium expelled by piston 4 is conducted to the discharge conduit 7 via the branch conduit 23 and the operating conduit 24.

[0050] The cylinders 1 and 2 are differently dimensioned. The active cross-sectional surface of piston 3 in the piston-side chamber of cylinder 1 has the same size as the active cross-sectional surface in the piston-rod-side space of cylinder 2 above piston 4. The active application surface of piston 3 in the piston-rod-side space is smaller than the active cross-sectional surface in the piston-side space of cylinder 1. This has the effect that the two cylinders 1, 2 move at the same speed when the pistons 3, 4 are being retracted.

[0051] If the shuttle valve 5 is moved to the left, the supply conduit 6 is connected via the operating conduit 24 and the branch conduit 23 to the piston-side chamber below piston 4 of cylinder 2. The piston 4 is displaced upwards. The pressure medium expelled by piston 4 is conducted via the conduit 22 to a location below piston 3 of cylinder 1 so at also said piston 3 will move upwards, said movement taking place at the same speed as the movement of piston 4. When the directional control valve 5 has been moved to the left and when the pistons 3, 4 move upwards, the valve 25 (shuttle valve) will prevent pressure medium, which is discharged from cylinder 1, from flowing off through the conduit 21, said pressure medium being, however, discharged through the conduits 26 and 23 into cylinder 2, whereby a faster movement of the two cylinders 1, 2 will be obtained.

[0052] In the embodiment shown in FIG. 4 (differently dimensioned cylinders 1, 2), two equalizing valves 27, 28 are provided in addition to the embodiment according to FIG. 3, said equalizing valves being implemented as pressure-limiting valves which prevent the force exerted by each cylinder from becoming excessively strong. The two equalizing valves 27, 28 are adjusted e.g. to a maximum pressure of 100 bar.

[0053] The equalizing valve 27 is pilot-controlled from the side of the operating conduit 21 in the direction of opening and is acted upon by a spring in the direction of closing. In addition, a pilot conduit is provided, which branches off from the conduit 22 and which is connected to the closing side of the equalizing valve 27. As soon as the pressure in the operating conduit 21 has reached the e.g. adjusted 100 bar, the equalizing valve 27 will connect the operating conduit 21 to the operating conduit 24 and thus to the discharge conduit 7. The equalizing valve 28 is spring loaded in the closing direction and additionally pressurized from the operating conduit 24 via a pilot conduit. The pilot conduit (indicated by a broken line) branching off from the conduit 22 acts on the equalizing valve 28 in the opening direction. As soon as the pressure on conduit 22 has reached an adjusted limit value (e.g. force of the spring at the equalizing valve 28), the equalizing valve 28 will open a flow connection through which pressure medium can flow off.

[0054] A silage cutter according to the present invention as disclosed in FIGS. 5 to 7 is movable on ground support wheels 32 and is adapted to be attached to a tractor by means of a pole 33. The silage has the form of a silage stock or silage block 31.

[0055] The device has provided therein a mixing chamber 34 for depositing cut-out silage for the purpose of transport. The mixing chamber 34 contains mixing devices by means of which the silage is loosened and mixed with other fodder component. The silage 31 is cut out with the aid of a frame comprising a first frame member 35 with a stationary knife 36 and a second frame member 37 provided with gripping devices 38 which engage the silage block when silage is being cut out. The first frame member 35 is pivotable about a hinge axle39 on the second frame member 37. The second frame member 37 is connected via a hinge axle 40 to the part of the device containing the mixing chamber 34.

[0056] The first frame member 36 is adapted to be moved relative to the second frame member 37 by means of the cylinders 1, 2 (cylinder 2 is not visible). By means of additional hydraulic cylinders 41, the second frame member 37, which has the first frame member 35 arranged thereon, can be adjusted relative to the mixing chamber 34.

[0057] In FIG. 5, the device, which occupies a ready-to-cut position, has been moved rearwards onto the silage block 31. By means of the cylinders 41, the second frame member 37 has been pivoted relative to the mixing chamber 34 downwards to such an extent that the gripping devices 38 touch the ground 42. The gripping devices 38, e.g. a flat metal plate, have been pushed along the ground 42 below the silage block 31.

[0058] The first frame member 35 is now pivoted downwards about the hinge axle 39 by means of the cylinders 1, 2 so that the knife 36 will be pressed along the broken line in FIG. 5 through the silage down to the position shown in FIG. 6. Subsequently, the second frame member 37 is pivoted together with the first frame member 35 about the hinge axle 40 by means of the cylinders 41 until the cut-out silage drops into the mixing chamber 34 (FIG. 7). The second frame member 37 forms in this case part of the wall of the mixing chamber 34.

[0059] The second frame member 37 consists of the platelike gripping devices 38 and of a flat part which follows said gripping devices 38 and on which the silage is deposited after having been cut out. The second frame member 37 is provided with side walls 44. The first frame member 35 consists of a U-shaped bent plate, the knife 36 being secured to the base of the U. The plate, which has provided thereon articulation points 46 for the cylinders 1, 2 and by means of which the frame member 35 is connected to the second frame member 37 via the hinge axle 39, defines two side walls 45.

[0060] Each side wall 45 has a lateral knife 47 provided thereon, which extends substantially at right angles to the knife 36. Both side walls 44 of the second frame member 37 are provided with a cutting device 43 towards which each lateral knife 47 moves when silage is being cut. A respective stop 48 serves to limit the movement of the first frame member 35 relative to the second frame member 37. A guide mechanism 49 of the first frame member 35 strikes on said stop 48 as soon as the cutting operation has been finished.

[0061] In FIG. 6, the cutting operation for a piece of silage 50 has been finished. The piece of silage is deposited in the mixing chamber 34 by moving the frame members 35, 37 about the hinge axle 40 (FIG. 7). Conduits in which the pressure medium is supplied to and discharged from the cylinders 41 for pivoting the first and second frame members 35, 37 are provided with check valves which are adapted to be controlled and unblocked, respectively, so that the second frame member 37 can temporarily be fixed at a specific position relative to the mixing chamber 34. In FIG. 8 and 9, the platelike gripping devices 38 extend up and below the silage block 31. The cutting device 43 on the side wall 44 of the second frame member 37 cooperates with the lateral knife 47 on the side wall 45 of the first frame member 35. Since the cutting edge of the lateral knife 47 is moved up to the cutting device 43, the silage located therebetween will be cut through.

[0062] In FIG. 9, the platelike knife with its cutting edge can be seen, said cutting edge being defined by a bevel 30 on the side of the knife 36 facing away from hinge axle 39.

[0063] In FIG. 10 (section in the plane X-X of FIG. 9), it can be seen how the lateral knife 47 is secured to the side wall 45 by means of screws 53; at the end of the cutting operation, said lateral knife 47is immersed in a groove provided between the cutting device 43 and the side wall 44. The cutting device 43 is secured to the side wall 44 by means of screws 54. With the aid of said groove, the silage can be cut through more effectively. If necessary, the cutting function in this area can be improved in that the cutting edge of the lateral knife 47 co-operates with an edge of the groove so that the effect produced is approximately a scissor-like cutting function.

[0064] According to FIG. 11, the side wall 44 is provided with the stop 48 which co-operates with the guide mechanism 49 on the side wall 45. The side wall 45 of the first frame member 35 is slid along the outer side of the side wall 44 of the second frame member 37. The guide mechanism 49 guarantees that said side wall is guided as planned and that no transverse movements will occur as well as that the motion will be limited as soon as the guide mechanism 49 strikes against the stop 48. This condition is shown in FIG. 11 as a cross-section in the intersecting plane XI-XI of FIG. 9. The stop 48 is adjusted such that it will already limit the motion before the cutting edge of the lateral knives 47 hits the bottom of the groove.

[0065] In a second embodiment according to FIGS. 12 to 15, the second frame member 37 with its gripping devices 38 is fixedly connected to the mixing chamber 34. The second frame member 37 forms an extension of the bottom of the mixing chamber 34. In this embodiment, the first frame member consists of a respective arm 56 and of a loading device 57 which is connected to said arm 56 and adapted to be pivoted about a hinge axle 58 and which is implemented in the form of a loading flap having secured thereto the knife 36 and the lateral knives 47. The lateral knives 47 have curved cutting edges, the hinge axle 58 being located at the centre of the curvature. The cutting device 43 is provided with a corresponding curvature (drawing cut).

[0066] The arms 56 are pivoted by means of the cylinders 1, 2 about the hinge axle 39 relative to the mixing chamber 34. The loading flap or loading device 57 is pivotable about a pivot point 58 at the ends of the arms 5 by means of two cylinders 59.

[0067] When silage is being cut out, the cylinders 59 are first adjusted to a specific length. The first frame member consisting of the arms 56 and the loading flap 57 moves from the position shown in FIG. 12 to the position shown in FIG. 13. Following this, the loading device 57 is pivoted to the position shown in FIG. 14 by means of the cylinders 59 (where appropriate, only one cylinder 59 may be provided in the middle); in the course of this process, the cut-out silage is transferred to the mixing chamber 34 where it can be mixed with other components with the aid of a mixing device 60, the loading device 57 defining part of the side wall of the mixing chamber 34.

[0068] According to FIG. 15, the device can be raised in an approximately vertical direction by adjusting the ground support wheels 32. Following this, the device can be attached to a tractor and transported away.

[0069] In the third embodiment of the silage cutter according to FIGS. 16 to 18, the second frame member 37 comprising the gripping devices 38 and the cutting device 43 is fixedly connected to the mixing chamber 34, in a manner corresponding to the second embodiment. The first frame member 35 does, however, not consist of parts which are movable relative to one another, but said first frame member 35 can be pivoted in its entirety about the hinge axle 39 on the mixing chamber 34 by means of the cylinders 1, 2. The hinge axle 39 is located at the top of the mixing chamber 34.

[0070] In said mixing chamber 34, a conveying device 62 is provided on the bottom of the chamber; by means of said conveying device, deposited silage can be transported in the interior of said mixing chamber 34 forwards in the direction of two dosing rolls 63 which deposit dosed amounts of the silage on a conveyor belt 64 for transporting said silage out of the device in a lateral direction.

[0071] The fourth embodiment of the silage cutter according to FIGS. 19 to 21 deviates from the first embodiment, since a respective hydraulic cylinder 66 is additionally provided on either side of the silage cutter. The first and second frame members 35 and 37 are moved towards each other by means of the cylinders 1, 2 in a scissorlike manner so as to cut the silage. The two cylinders 66 assist in this process with additional shearing forces so as to increase the cutting force. Each cylinder 66 acts on an extension of the first frame member 35 projecting beyond the hinge axle 39 on the side facing away from the knife 36. In spite of the higher cutting forces, a deformation of the frame is prevented by hydraulically guaranteeing that the lengths of the cylinders 1, 2 are always identical or rather that the cylinders adjusting movements are identical. The cutting force can substantially be increased by the cylinders 66 in this way, without any additional devices being required in addition to these cylinders 66. The cylinders 66 are simple hydraulic cylinders exerting approximately identical additional forces so that the dimensions of said cylinders 1, 2 need not exceed a certain limit.

[0072] In FIG. 22, the flow divider 14 in the operating conduits 15, 16 is followed by a compensating regulating or control valve 17′, e.g. a 4/3-way control valve which has a spring-centered open neutral position and both sides of which are hydraulically actuated. The control connections of the valve 17′ are connected to the operating conduits 15, 16 via pilot conduits 18′, 18″. If, e.g. during a silage cutting operation, cylinder 1 operates against a lower counterpressure than cylinder 2, the valve 17′ will be moved to the left and the pressure medium flow in the operating conduit 15 will be throttled, if necessary up to complete blockage. Cylinder 1 cannot advance relative to cylinder 2.

[0073]FIG. 23 shows a compensating control valve 17″, e.g. a 4/3-way control valve with a spring-centered neutral position at which two control conduits 67, 68 are connected to one another and to a common pressure-medium supply conduit 11, and with hydraulic opposite actuation from the pilot conduits 18′, 18″ of a pilot circuit branching off from said operating conduits 15, 16. During silage cutting, the second inlet of the valve 17″ is open to the discharge conduit 8 leading to the directional control valve 5. The conduits 9, 10 have brake valves 69, 70 provided therein, e.g. pressure-limiting valves which are adapted to be unblocked against spring force by control pressures derived from the respective cylinder and/or from the control conduits 67, 68. Each valve 69, 70 is by passed by a check valve 74 in the bypass, said check valve 74 opening in the flow-in direction to the piston-side chambers of the cylinders 1, 2 (directional control valve 5 moved to the right). When the directional control valve 5 is moved to the left (cutting position), the two brake valves 69, 70 are kept open by pressure from the pressure-medium supply conduit 11, the valve 17″ is kept at the position shown and the control conduits 67, 68 are kept open, as long as no substantial pressure difference (corresponding e.g. to the force of the centering springs of the valve 17″) occurs between the operating conduits 15, 16. None of the cylinders is decelerated on the discharge side. If the pressure in operating conduit 16 becomes higher than that in operating conduit 15, the compensating control valve 17″ will be moved to the left from the pilot conduit 18″. The brake valve 70 is kept open via the control conduit 68 from the pressure-medium supply line 11. The brake valve 69 is relieved via the control conduit 67 to the discharge conduit 7, said brake valve 69 being kept by its spring at a shut-off position or at a throttling position. The cylinder 1, which is just operating against a lower counterpressure, is decelerated on the discharge side and forced to move synchronously with cylinder 2, which is just operating against the higher counterpressure.

[0074] In FIG. 24, the compensating control valve is provided directly between the conduits 9, 10 and the discharge conduit 8 leading to the directional control valve 5, said compensating control valve being controlled from the pilot conduits 18′, 18″. As long as no substantial pressure difference occurs between the operating conduits 15, 16 downstream of the flow divider 14 during silage cutting, the valve 17″ will not intervene. Only if a pressure difference of a predetermined magnitude occurs, the valve 17″ will decelerate cylinder 1 or 2, which is just operating against the lower counterpressure, on the discharge side until the pressure difference between the operating conduits has been equalized.

[0075] In FIG. 25, the conduits 9, 10 on the discharge side (during silage cutting) have arranged therein biased control valves 71, 72 which are controlled crosswise from the operating conduits 15, 16 via the pilot conduits 18′, 18. Each biased valve 72 is adjustable, e.g. gradually, between an open position and a blocking position and is urged into the open position by a spring 73 and the pressure in its pilot conduit 18′ or 18″. At least during silage cutting, it can, however, be moved towards its blocking position from the respective other pilot conduit 18″ or 18′ when a certain pressure difference occurs between the operating conduits. The respective cylinder 1 or 2 operating against the lower counterpressure is then decelerated or biased on the discharge side until the pressure difference between the operating conduits has been equalized. Fundamentally, the flow divider 14 apportions to each cylinder the same amount of pressure medium per unit time independently of the counterpressure of each cylinder 1, 2 so that the cylinders move in synchronism. However, due to production and function tolerances, a tendency towards deviations may perhaps occur temporarily, said tendency towards deviations being compensated for by the additional control and regulating components according to FIGS. 22 to 25. 

1. A silage cutter comprising a frame which consists of a first frame member having attached thereto a knife and a second frame member provided with gripping devices for gripping the silage, said first frame member being supported on said second frame member such that it is rotatable about a hinge axle, and further comprising drive mechanisms for moving said first and second frame members relative to each other, characterized in that the drive mechanisms comprise two hydraulic cylinders (1, 2) which are each articulated on said first and second frame members (35, 37), that a hydraulic device is provided by means of which the same length and synchronous movement, respectively, can be adjusted for both hydraulic cylinders (1, 2), at least for the silage cutting operation, and that the differential distance between the hinge axle (39) and the part of the gripping devices (38) which is most remote from said hinge axle (39) is larger than the distance between the hinge axle (39) and the knife (36).
 2. A silage cutter according to claim 1, characterized in that the hydraulic cylinders (1, 2) in the drive mechanisms are hydraulically connected in series in such a way that the hydraulic medium from one cylinder is conducted to the respective other cylinder, preferably both cylinders (1, 2) having piston-side and piston-rod-side chambers and the active cross-sectional surface on the piston-rod side of one cylinder corresponding, at least to a large extent, to the active cross-sectional surface on the piston side of the other cylinder so as to adjust equal adjustment speeds in the series connection of the two cylinders (1, 2).
 3. A silage cutter according to claim 1, characterized in that the hydraulic cylinders (1, 2) in the drive mechanism are identically dimensioned and hydraulically connected in parallel.
 4. A silage cutter according to one of the claims 2 and 3, characterized in that adjustable maximum-pressure or differential-pressure limiting valves (17, 19, 27, 28) are provided, which limit the maximum possible pressure in each cylinder (1, 2) or the maximum possible differential pressure between the cylinders (1, 2) to a set value.
 5. A silage cutter according to claim 1, characterized in that the distance between the hinge axle (39) and the articulation point (46, 58) of the cylinders (1, 2) on the first frame member (35) is larger than half the distance between the hinge axle (39) and the knife (36), preferably larger than two thirds, most preferably larger than three quarters of this distance.
 6. A silage cutter according to claim 1, characterized in that the distance between the hinge axle (39) and the articulation point of each cylinder (1, 2) on the second frame member (37) is larger than half the distance between the hinge axle (39) and the gripping devices (38), preferably larger than two thirds, most preferably larger than three quarters of this distance.
 7. A silage cutter according to claim 1, characterized in that the first frame member (35) is provided with at least one lateral knife (47) which is oriented at least approximately at right angles to the knife (36) and/or at least approximately radially to the hinge axle (39).
 8. A silage cutter according to claim 7, characterized in that each lateral knife (47) has a curved, preferably a convex cutting surface.
 9. A silage cutter according to at least one of the claims 1 to 8, characterized in that the knife (36) and/or the lateral knife (47) have/has a cutting edge which is knurled or wavy and which includes parts that extend at a specific angle relative to one another.
 10. A silage cutter according to claim 9, characterized in that the distance between downwardly extending portions of the cutting edge is smaller than 8 cm, preferably smaller than 6 cm, or most preferably smaller than 4 cm.
 11. A silage cutter according to claim 1, characterized in that the knife (36) is a metal plate provided with an edge-side bevel (30) on the side of the plate facing away from the hinge axle (39), said bevel (30) defining a cutting edge.
 12. A silage cutter according to one of the claims 1 to 11, characterized in that the second frame member (37) is provided with a cutting device (43) which is implemented such that it is adapted to co-operate with the knife (36) and/or each lateral knife (47).
 13. A silage cutter according to claim 12, characterized in that the cutting device (43) is provided with a counteredge, preferably for a scissor-like cut with the cutting edge of the knife (36) or of the lateral knife (47).
 14. A silage cutter according to one of the claims 12 or 13, characterized in that the cutting device (43) is provided with an immersion groove for the cutting edge of the knife (36) or for the lateral knife (47).
 15. A silage cutter according to claim 1, characterized in that the gripping devices (38) comprise a platelike member provided with a sharp edge or teeth which is/are adapted to be pressed into a silage block.
 16. A silage cutter according to claim 1, characterized in that the differential distance ranges between at least approx. 5 cm and approx. 15 cm.
 17. A silage cutter according to claim 1, characterized in that the first and/or second frame member(s) (35, 37) is/are provided with guide mechanisms (48, 49) for at least a sub-element of said second and said first frame member, respectively, and for transversely supporting the frame members against movements and/or deformations of the hinge axle (39).
 18. A silage cutter according to claim 17, characterized in that the guide mechanisms (48, 19) are provided with a limiting stop (48) for the relative movement between said first and second frame members (35, 37).
 19. A silage cutter according to at least one of the claims 1 to 18, characterized in that a silage deposit/mixing chamber (34) comprising a mixing chamber wall is provided, and that preferably the second frame member (37) defines part of said mixing chamber wall.
 20. A silage cutter according to claim 19, characterized in that the second frame member (37) is tiltably secured to the silage deposit/mixing chamber (34) by means of a hinge (40).
 21. A silage cutter according to at least one of the claims 1 to 19, characterized in that the second frame member (37) is fixedly connected to the mixing chamber (34) and that an extension thereof defines the bottom of said mixing chamber, that the first frame member comprises respective arms (56), which are each pivotable about the hinge axle (39) on the mixing chamber (34), and a loading flap (57) having the knife (36) secured to the lower edge thereof, and that the loading flap (57) is movable relative to said arms (56) in a hinge (58) or in a sliding mechanism.
 22. A silage cutter according to claim 1, characterized in that said silage cutter is adapted to be moved up and down on ground support wheels (32) in an approximately vertical direction.
 23. A silage cutter according to one at least of the claims 1 to 21, characterized in that the second frame member (37) is supported on the mixing chamber (34) by means of two hydraulic cylinders (41) such that it is pivotable relative to said mixing chamber, and that in the application conduits of said cylinders (41) control valves, e.g. check valves, are provided by means of which the effective length of both cylinders (41) can be fixed at least temporarily.
 24. A silage cutter according to claim 3, characterized in that, for adjusting respective identical lengths of the two hydraulic cylinders (1, 2) which are connected in parallel, a hydraulic flow divider (14) is provided for identical pressure medium flows between a common pressure-medium supply conduit (11) an operating conduits (15, 16) leading to the e.g. piston-rod-side chambers of the cylinders (1, 2) which are adapted to be pressurized in the cutting direction.
 25. A silage cutter according to claim 24, characterized in that the operating conduits (15, 16) have provided between them a pressure-difference sensing valve (17) connected via a pilot conduit (18) to the closing side of a pressure-limiting valve which is provided as an equalizing valve (19) between the pressure-medium supply conduit (11) and a discharge conduit (8) of both cylinders (1, 2), said discharge conduit (8) being adapted to be connected to a discharge conduit (7), and that this equalizing valve (19) is pilot-controlled from the pressure-supply conduit (11) in the opening direction against the force of a spring and acts as a differential-pressure limiting valve between the operating conduits (15, 16).
 26. A silage cutter according to claim 2, characterized in that the series-connected hydraulic cylinders (1, 2) have provided between them two equalizing valves (27, 28) which each supervise one cylinder (1, 2) and which are implemented as pilot-controlled pressure-limiting valves, said equalizing valves (27, 28) having a maximum-pressure limiting function towards the discharge conduit (7).
 27. A silage cutter according to claim 24, characterized in that a compensating control valve (17′) responding to a pressure difference between the operating conduits (15, 16) is provided directly in said operating conduits (16, 16) between the flow divider (14) and the cylinder chambers which are adapted to be pressurized in the cutting direction, said compensating control valve (17′) being preferably a multi-way/multi-position valve which permits passage at its neutral position and which, at each compensating position, throttles up to blockage the respective operating conduit (15, 16) having the lower pressure.
 28. A silage cutter according to claim 24, characterized in that a pilot circuit (18, 18″), which is connected in parallel to the operating conduits (15, 16), controls a compensating control valve (17″) which is arranged in pilot-control paths (67, 68) between the pressure-medium supply conduit and a discharge conduit (8), respectively, and a respective brake valve (69, 70) which is provided on the discharge side of each cylinder (1, 2) during silage cutting and which s preferably pilot controlled by the discharge pressure against the force of a spring, said brake valve (69, 70) decelerating the cylinder (1, 2) operating against the lower counterpressure during silage cutting.
 29. A silage cutter according to claim 24, characterized in that a pilot circuit (18′, 18″), which is connected in parallel to the operating conduits (15, 16), controls a compensating control valve (17″), which is arranged between conduits (9, 10) constituting discharge-side conduits during silage cutting and a common discharge conduit (8), and decelerates the cylinder (1, 2) operating against the lower counterpressure in response to a pressure difference between the operating conduits (15, 16).
 30. A silage cutter according to claim 24, characterized in that a pilot circuit (18, 18″) is provided, which is connected in parallel to the operating conduits (15, 16) and which senses pressure differences between the operating conduits (15, 16), that each conduit (9, 10) of each cylinder (1, 2) constituting a discharge-side conduit during silage cutting and leading to the common discharge conduit (8) has arranged therein a biased control valve (71, 72), which is adapted to be displaced between a spring-conditioned open position and a blocking position and which, during silage cutting, is pressurized parallel to the spring (73) via the pilot circuit (18′, 18) with pilot pressure of its associated cylinder in the direction of the open position and with pilot pressure of the respective other cylinder in the direction of the blocking position in such a way that the respective cylinder (1, 2) operating against the lower counterpressure is decelerated on the discharge side. 